Diff lock problem 240...

Ok MF experts, I've been trying to get the diff lock working on the 240, I asked about this one other time and here is where I am at:

It worked great a few years back, I parked the tractor inside for the winter, and went to use the lock the next spring and it won't "lock"

It hasn't worked in a few years and I'm finally getting around to it.

While it was still working I had adjusted the pedal height when engaged to be what the manual stated as before the pedal would touch the floor board when engaged.

The pedal is tight on the splined shaft, and moves up and down slightly while rotating the shaft slightly, and the shaft will move in and out slightly in the housing, I can stand with my body weight on the pedal while driving and it will not drop in to lock(weaving slightly while driving slowly forward (Low 1st) to try and get the axle halves aligned the same way when the lock was working)

I've had the tractor parked on a slant for 4 weeks now with the right rear wheel up on a tall block trying to get penetrating oil to work it's way in.

Am I to the point this problem is internal? or should I keep trying what I'm doing and hope it will eventually "come free"

I have the service manual but am not looking forward to taking the trumpet housing off, and likely won't in the immediate future.

Hello 495,
The image shows the workings of the diff lock unit. This is for a 135 but as far as I know they are the same unless you have square axles which I'm not aware of.
There should be no need to exert any excessive force. If it won't engage at light pressure there is something wrong. The easiest way to test it is to jack and support the RH rear wheel clear of the ground. Turn the wheel by hand and press the pedal by hand. If its working, you will feel it 'drop in'. I have never known one to seize so I think that can be ruled out. Does the pedal return fully? You say that you have adjusted correctly but there is no sign of engagement. Test again as above. When driving with the diff engaged on tarmac or concrete the tractor will always pull itself back to straight ahead. This is not so strong on grass. A very likely cause of the problem is a pin (MF 16 750X) which passes through the cap (71) and through the shaft (74). This pin is not shown on this image. Its possible that other item/s may have broken but very unlikely given normal use.
Removal of the axle housing is straight forward providing that the tractor is suitable supported.
Diff lock components are then easily accessed.
DavidP, South Wales

Thanks David, it does have round housings and your diagram is similar, but not identical to what is shown in my I&T shop manual (manual covers 230/235/240/245/250 so US built tractors and UK built) but from a different angle.



The pedal does not drop down at all to engage the lock, when it did work it was properly adjusted according to my 240/250 manual. The spring return is working properly (external "15" on my diagram") The lock isn't engaging at all as I can turn full lock and not have the tires scuff the ground when pushing the pedal.

The shaft, what appears to be "67" in your diagram and part of "11" in mine appears to be free, I can see movement and the shaft has end play when I wiggle the pedal by hand.

The pin you are talking about sounds like "12" on my diagram, but it that was sheared off the pedal should drop freely, but it doesn't (?) It feels like the shaft is prevented from turning even though it isn't seized in place.

It's almost like "4" and "11" are binding or "7" is stuck in place.

After reading your comments, sounds like I will have to take this apart...

Hello,
Your number '7' being seized would certainly appear to give all of the problems that you describe. Was the diff-lock used from time to time previously?
As there is little more that you can do externally id does look as if surgery is required.
If you do not have a cab fitted then the job will be much easier. If you have some means of lifting the axle that would be advisable. A trolley jack is ok but it would be helpful if you can secure the axle via the fender bolt holes to the jack-head. It is fairly heavy but it is also unweildy. When you withdraw the axle ensure that the differential remains behind.
DavidP

The lock was used lots the summer before it stopped working, then the tractor went into storage for that winter and wasn't driven for about 5 months, and the lock wouldn't work after that.

No cab, but the 2 post ROPS has to come clear as it bolts to the axle housing.



I guess I'm going to have to leave it as is for the next little while if I have to open it up, I have to get tools/lift to remove the axle housing as well as fit it in time wise to do the job.

Thanks for your advice, it is most appreciated.

Can almost smell the hay. Just what I need on a miserable winters day.
DavidP

I have come on several tractors with the diff-lock seized, but
they were much older and more rusted than your tractor which
looks immaculate . In most cases it took heat from the
oxyacetylene set to free it and then a new seal was needed on
the shaft, but some locks I have managed to free off with
patience, plenty of oil and a heavy hammer! Do not try to beat
the pedal down but hit it up and down, this should help shock
the rust/binding. Do not hit the folding pedal if that is the type
on your tractor,rather hit the arm of the pedal. I have sheared off
the bolt through the flip-up pedal before,so be careful. Good
luck
Sam

I know, it's awful, I was looking through my photo albums and was wishing I was haying again....

(quoted from post at 18:08:55 12/12/10) I have come on several tractors with the diff-lock seized, but
they were much older and more rusted than your tractor which
looks immaculate . In most cases it took heat from the
oxyacetylene set to free it and then a new seal was needed on
the shaft, but some locks I have managed to free off with
patience, plenty of oil and a heavy hammer! Do not try to beat
the pedal down but hit it up and down, this should help shock
the rust/binding. Do not hit the folding pedal if that is the type
on your tractor,rather hit the arm of the pedal. I have sheared off
the bolt through the flip-up pedal before,so be careful. Good
luck
Sam

Click to expand...

Hmm, I think the pedal does fold (bolted to shaft). The pedal shaft appears free, I may give that a shot, shock loose inside, one last ditch effort before giving up for a while.

Thanks.